package com.sy.simpleegg.platform.whm.util;
import java.io.UnsupportedEncodingException;

public class Base64Utils {
   private static char[] base64EncodeChars = new char[]
           { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
                   'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
                   'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5',
                   '6', '7', '8', '9', '+', '/' };
   private static byte[] base64DecodeChars = new byte[]
           { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
                   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53,
                   54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
                   12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29,
                   30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1,
                   -1, -1, -1 };

   /**
    * 加密
    *
    * @param data
    * @return
    */
   public static String encode(byte[] data) {
      StringBuffer sb = new StringBuffer();
      int len = data.length;
      int i = 0;
      int b1, b2, b3;
      while (i < len) {
         b1 = data[i++] & 0xff;
         if (i == len){
            sb.append(base64EncodeChars[b1 >>> 2]);
            sb.append(base64EncodeChars[(b1 & 0x3) << 4]);
            sb.append("==");
            break;
         }
         b2 = data[i++] & 0xff;
         if (i == len) {
            sb.append(base64EncodeChars[b1 >>> 2]);
            sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
            sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);
            sb.append("=");
            break;
         }
         b3 = data[i++] & 0xff;
         sb.append(base64EncodeChars[b1 >>> 2]);
         sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
         sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);
         sb.append(base64EncodeChars[b3 & 0x3f]);
      }
      return sb.toString();
   }

   /**
    * 解密
    *
    * @param str
    * @return
    */
   public static byte[] decode(String str) {
      try{
         return decodePrivate(str);
      } catch (UnsupportedEncodingException e) {
         e.printStackTrace();
      }
      return new byte[]
              {};
   }
   private static byte[] decodePrivate(String str) throws UnsupportedEncodingException {
      StringBuffer sb = new StringBuffer();
      byte[] data = null;
      data = str.getBytes("US-ASCII");
      int len = data.length;
      int i = 0;
      int b1, b2, b3, b4;
      while (i < len){
         do {
            b1 = base64DecodeChars[data[i++]];
         } while (i < len && b1 == -1);
         if (b1 == -1)
            break;
         do {
            b2 = base64DecodeChars[data[i++]];
         } while (i < len && b2 == -1);
         if (b2 == -1)
            break;
         sb.append((char) ((b1 << 2) | ((b2 & 0x30) >>> 4)));
         do{
            b3 = data[i++];
            if (b3 == 61)
               return sb.toString().getBytes("iso8859-1");
            b3 = base64DecodeChars[b3];
         } while (i < len && b3 == -1);
         if (b3 == -1)
            break;
         sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));
         do {
            b4 = data[i++];
            if (b4 == 61)
               return sb.toString().getBytes("iso8859-1");
            b4 = base64DecodeChars[b4];
         } while (i < len && b4 == -1);
         if (b4 == -1)
            break;
         sb.append((char) (((b3 & 0x03) << 6) | b4));
      }
      return sb.toString().getBytes("iso8859-1");
   }
}
